Electrodeless lamps are known; see, for example, U.S. Pat. Nos. 3,942,058; 4,427,924; 4,427,922; 4,783,615; and 4,810,938. Such lamps have been fabricated from quartz arc tubes. Greater efficiences could be realized if rare earth fills could be employed; however, to take advantage of some of these fill it is necessary, because of the low vapor pressure of some of the ingredients when in the iodide form, to increase the operating temperature of the arc tube to the point that the lifetime of the lamps using these arc tubes becomes too limited.